Samsung TV Vertical Lines Fix Guide – Gate Drive Fault Diagnosis and Fix
Introduce fault
Samsung TV Vertical Lines Repair – Gate Drive Fault Diagnosis and Repair. This Samsung LED TV, model number UA43KU7000K, came to my workshop for repair. The customer said that we were watching a program, and suddenly the picture disappeared, and these lines appeared vertically on it, and then we turned off the set. I turned on the set and saw that at first the picture was completely blank, and then slowly vertical lines started forming in it. This was a fault in it. So I told the customer to leave it. This is a screen problem. I will diagnose it, and then I will tell you how it will be fixed and what the cost will be. The customer said that it is okay to keep it and let us fix it.
Fault Diagnosis
I opened this set in my workshop, removed its back cover, cleaned it, dusted it, etc., and saw that in this set, there are two separate FFC ribbon cables for the panel going to the system board. Now, I removed these ribbon cables one by one and turned on the TV. Then, the image on one side became mine. This meant that there was some short circuit on the other side due to which the screen was not working. Obviously, this short circuit could be of the gate drive, which we call CKV in technical language. These gate drives usually get shorted inside the glass, either with each other or with ground somewhere, due to which the entire scanning system is damaged.
- Gate Drive Short Circuit Cause – CKV
- Scanning System Failure
Gate Drive Short Circuit Diagnosis
When it was confirmed that the fault was on this side of the screen, I checked the gate drive on that side with a meter. Its test points were made on the scalar strip. There were a total of eight gate drives. I checked each drive with my multimeter, and the short circuit I found was between CKV and CKV2. The resistance I found between the two was approximately 120 ohms. This meant that these two gate drives were shorted together from inside the glass. Now I had only one way to isolate all these gate drives so that scanning could start and an image could be created. I isolated them by applying tape on the FFC cable where these eight gate drive points were.
- Fault confirmed on one side of the screen after testing.
- A short circuit was detected between the CKV and CKV2 gate drives (120 ohms resistance).
- Gate drives are isolated by applying tape on the FFC cable to restore image scanning.
Gate Drive Isolation Fix – Cost-Effective Repair
After isolating its gate drive, I connected the screen and its FFC cable and turned on the TV. My screen started working perfectly. There was no line in it. It created a perfect picture. Thus, my fault was fixed. I want to tell you that this is not a proper solution, but we usually do this. You can call it a trick that you can use to drive. It benefits both you and the customer. Because a new screen is quite expensive, it benefits the customer. I would usually advise the technicians that if you do such a job, first tell the customer that yes, we will do this job so that the matter is clear. The customer should know how my work is being done. This also benefits you, and the customer should also be clear about how we will remove this fault.
- The screen worked perfectly after isolating the faulty gate drive.
- The tape isolation method removed vertical lines and restored a clear picture
- Cost-effective fix that benefits both technician and customer compared to expensive screen replacement.
- It’s important to inform the customer before applying this non-permanent trick for transparency.
Conclusion
You saw how we repaired the vertical lines in the Samsung model. In this case, there was a problem of gate drive short circuit on one side of the screen. So we first diagnosed which side it was, and then we isolated this side by putting tape on its FFC cable. In this way, our fault was fixed. The picture on this TV is absolutely great, and the picture is fine, as if it were a brand-new screen. But usually it does not happen that we isolate the gate drive and some problem remains in it. Some lines remain, or some lines appear. Horizontal lines appear. This is a common fault in this. The screen does not necessarily have to be in Samsung; it can also appear on any other screen. In this case, there is a 50-50 chance of being repaired.
If you want to read our article on LED TV Black Screen Issue After Startup, click here.
Shaukat Ali
Shaukat Ali is a professional Sony LED TV repair technician with over 30 years of experience. He specializes in diagnosing and fixing complex display and board-level faults. Based in Lahore, he shares real-world repair cases to help both customers and fellow technicians.
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